Blow molding machines comprising an extrusion station and two calibrating stations arranged opposite to each other, relative to the extrusion station have been proposed with such blow-molding machines including two closing systems each intended for one side of blow molds and assigned to one of the calibrating stations, in which plastic hollow bodies are blown in alternating succession at the two calibrating stations. A gripper mechanism is generally provided by which the blown hollow bodies can be transferred to finishing stations arranged along a line in one plane for further processing, with such further processing including, for example, pinch-off removal and/or the cutting or punching operation.
Blow-molding machines of this type have been generally known. Typical manufacturers of such machines are, for example, Bekum, Kautex and Battenfeld-Fischer.
The known blow-molding machines consist of a basic machine comprising an extrusion station and two calibrating stations arranged laterally thereof, as well as closing systems assigned to the calibrating stations and carrying each two mold halves which form the blow mold of the respective closing system and can be loaded alternately with hose-like parisons of a plasticized synthetic material that have been produced at the extrusion station. In addition to these machine elements constituting the basic machine, there are provided finishing stations which are arranged downstream of the two calibrating stations and which are intended, for example, for punching grip recesses, for example into bottles, and/or for removing pinch-off from the hollow bodies emerging from the blow molds and/or for testing the hollow bodies for tightness, with it being understood that in the case of blow-molding machines having two calibrating stations all these finishing stations must be provided twice, in the normal arrangement usual for blow-molding machines having only a single calibrating station.
If the hollow plastic bodies, after having been blow-molded and given their final form in subsequent finishing stations, are to be removed from the system at a single point of discharge, possibly in uniform orientation, expensive transfer and conveying means are additionally required for guiding the hollow bodies, which have been molded at different calibrating stations, to a common delivery station.
Due to the above noted constructional and functional properties, these blow-molding machines at least the following disadvantages.
1. They require much space along the plane(s) marked by the line of finishing stations.
2. They require a great amount of technical input, thus causing high production expenses, due to the double line of finishing stations. This disadvantage is even aggravated by the fact that two sets have to be provided also of the transfer and retainer shells, which have to be adapted to the shape of the hollow bodies produced and which are rather expensive to produce. The same applies analogously for punching tools, which have to be adapted for example to the shape of the grip recesses, and for testing equipment and other finishing tools.
3. They require additional input for the conveying and transfer installations necessary for transporting the finished hollow bodies to a common delivery station.